Many types of documents as labels, authentication tags, certificates, and guarantees are used in large quantities and must be processed by machine to achieve reasonable handling costs. Such documents may be encoded with machine-readable data and include a section that exhibits an identifying characteristic. For example, the document might be made of fibrous material, e.g. bond paper, having a varying translucency pattern. Scanning a light beam over a specific section of the document will modulate the light to provide an individual characteristic pattern identifying the document. As the pattern is repeatable, it has been proposed to record select data from the pattern on the document to enable future verification. Accordingly, such documents have been used as authenticators to verify various objects including merchandise.
Processing authentication documents as described above has generally involved machine operations to sense the identifying physical characteristic of the document itself, then reading the reference data for select comparison. Pursuing the above example, the translucency pattern of a paper document would be sensed for comparison with a machine-readable record of the pattern that is printed on the label. Such techniques have proven to be quite successful in combating counterfeits.
With respect to authentication documents as explained above, the printed data is sometimes called an "escort memory". Normally, the escort memory records data to indicate specific samples of the characteristic pattern sensed from the media. Accordingly, the data might specify a set of samples manifesting specific locations in the data section along with translucency values at such locations. In addition to an escort memory, the document also includes some form of reference for locating the data section. For example, the section might be located by an edge of the document or a printed reference target.
Considering an effective authentication system of the prior art, an optical target is printed on a document for use as a position reference. That is, the target defines a section of the document that is to be sensed for a repeatable characteristic pattern.
In operation, the section is sensed to produce signal-represented data that is individual to the document. The data is processed as by a data compression algorithm to produce a character string that identifies select locations of the section and the document character at such locations. The character string is then printed on the document in a machine readable form as the escort memory.
To authenticate the document the machine-readable characters (escort memory) are read and the target-designated section of the document is sensed. The two forms of data are then compared to test the recently observed character of the document with the recorded character. Of course, a favorable comparison verifies the document.
While systems of the prior art, as considered above, have been effective, certain limitations and disadvantages exist in relation to the escort memory. First, optical code readers (alphanumeric) are relatively expensive with the consequence that verification equipment is necessarily expensive. Second, an escort memory in the form of printed characters requires substantial space on the document. Expressed in another way, the information bit density for a printed escort memory is relatively low. As a third factor for reliable operation of an optical code reader, an escort memory in the form of optical characters requires a high quality printing.
An alternative encoding approach has been proposed for an escort memory in the form of bar codes. However, that alternative affords little advantage with respect to space requirements and the printing quality for a bar code reader must be comparable or perhaps even better than that required for an optical code reader. Thus, bar codes for the escort memory offer little advantage.
In the final analysis, a need continues to exist for an improved authentication device with the reliability of prior devices yet offering improvement with respect to the above considerations.
In general, the present invention includes an authentication device constituted by a sheet of medium including a characteristic section capable of individually identifying the device, e.g. as by light translucency. The characteristic section is marked or specified by a magnetic-ink mark (target) on the sheet of medium, the mark being of a shape and form to precisely locate the section. Additionally, the magnetic-ink mark is magnetized to indicate selected locations in the characteristic section and related values of the characteristic at such locations. Accordingly the target performs the joint function of specifying the characteristic section and providing the escort. The invention further includes the systems of producing and verifying such authentication devices.
As disclosed in detail below, the development hereof may be variously implemented using different media, different ink compositions, and different recording techniques. For example, the media may comprise paper with varying translucency or various other sheet media with an individual repeatable characteristic.